Earlier today, the Mr Rossington's father posted on the site of his son's employer, the Ambulance service, thanking authorities for their efforts.

The air and sea search scoured 1360 square nautical miles off the Forster coast where the pair went overboard. Local marine rescue had also alerted passing ships to keep an eye out for the couple.

Detective Superintendant Mark Hutchings said on Friday weather conditions and the medical health of the couple strengthened rescue hopes, but the pair went overboard dozens of hours ago.

"It has been a long time since this incident occurred and whilst we hold out some hope, the hope is fading," he said.

Earlier, police said it was unclear whether the pair jumped or fell.

Carnival chief executive Ann Sherry has defended the ship's safety and security measures and says the gap in time from when the couple went overboard to when crew realised is because no-one saw the incident.

"The issue of the gap in the timing, it partly goes to a man overboard protocol," she said.

"We didn't realise the couple were missing until the disembarkation."

'Shocking news'

Barraba resident Paula McIvor says it is devastating news.

"It's very sad in Barraba. The community is very, very saddened," he said.

"We're a very tight-knit little community here. We all know each other and we're very shocked by the news.

"We feel for all the relatives and family of these people."

Another local resident, John Bishton, says the 30-year-old paramedic is well-known and well-liked.

"He's a consummate professional," he said.

The search had stretched from Sydney Harbour up the coast to Newcastle, following the track of the cruise ship.